AN ESTRANGED son knocked his father unconscious in a fatal one-punch attack in broad daylight after randomly spotting him walking down the street in Brisbane’s CBD, police will allege.

Morgan Alexander Isles-English last night had his charge upgraded to unlawful striking causing death after his father Mark, 53, succumbed to his injuries in the Royal Brisbane and Women’s Hospital.

Hours earlier, a distressed Isles-English broke down and sobbed in the dock when he fronted Brisbane Magistrates Court on one count of grievous bodily harm over the ­alleged incident on Monday.

Mark McGrice and his partner.In emotional scenes, the 25-year-old paced back and forth in the glass-walled ­prisoner’s dock, crying out to a woman in the public gallery that “I love you, Mum” and asking whether “he was awake”.

Defence lawyer Brendan Beavon, from Russo Lawyers, did not make an application for bail on his client’s behalf and requested the matter be adjourned to next month.

No details of the alleged attack were read out in court but it is believed Isles-English was in a bar when he spotted his father Mark McGrice – also known as Mark English – walking down the street with his partner about 4pm on Monday.

There were reports that the pair had not seen each other for four years.

Police allege the pair had a “brief verbal exchange” on Ann St before Isles-English hit his father in the mouth.

The mother of the accused Morgan Isles-English leaves court.The father fell back and struck his head on the ground, losing consciousness.

Police said the Ashmore man’s partner, who was not physically injured, performed first aid on him before he was rushed to the RBWH with life-threatening injuries.

Shortly before 5pm yes­terday, Queensland police ­released a statement confirming that the 53-year-old had died.

Mr English, who was born in Victoria, described himself on social media as a chef who was a “jackaroo of all trades, master of one” and wrote that he was “living life large with the most wonderful life partner your soul could find”.

Isles-English is expected to re-appear in court today on the upgraded charge, which carries a maximum penalty of life imprisonment.

The accused’s mother ­declined to speak to media as she left the courthouse ­yesterday.

A family tragedy ....a chance encounter after 4 years estranged both in the wrong place at the wrong time son acted impulsively a very sad case for all concerned.